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Native and activated antithrombin inhibits TMPRSS2 activity and SARS-CoV-2 infection
Lukas Wettstein1, Patrick Immenschuh1, Tatjana Weil1
1Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany.
Abstract:
Host cell proteases such as TMPRSS2 are critical determinants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) tropism and pathogenesis. Here, we show that antithrombin (AT), an endogenous serine protease inhibitor regulating coagulation, is a broad-spectrum inhibitor of coronavirus infection. Molecular docking and enzyme activity assays demonstrate that AT binds and inhibits TMPRSS2, a serine protease that primes the Spike proteins of coronaviruses for subsequent fusion. Consequently, AT blocks entry driven by the Spikes of SARS-CoV, MERS-CoV, hCoV-229E, SARS-CoV-2 and its variants of concern including Omicron, and suppresses lung cell infection with genuine SARS-CoV-2. Thus, AT is an endogenous inhibitor of SARS-CoV-2 that may be involved in COVID-19 pathogenesis. We further demonstrate that activation of AT by anticoagulants, such as heparin or fondaparinux, increases the anti-TMPRSS2 and anti-SARS-CoV-2 activity of AT, suggesting that repurposing of native and activated AT for COVID-19 treatment should be explored.
Insights
Antithrombin (AT), a natural protease inhibitor, broadly inhibits coronavirus infections by blocking TMPRSS2, a key enzyme for viral entry. Activating AT with anticoagulants enhances its anti-SARS-CoV-2 effects, suggesting therapeutic potential for COVID-19.
Area of Science:
- Virology
- Biochemistry
- Pharmacology
Background:
- Host cell proteases, like TMPRSS2, are crucial for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry and disease development.
- Understanding viral entry mechanisms is key to developing effective antiviral strategies against coronaviruses.
Purpose of the Study:
- To investigate the potential of antithrombin (AT), an endogenous serine protease inhibitor, as a broad-spectrum inhibitor of coronavirus infection.
- To explore the mechanism by which AT inhibits TMPRSS2 and its implications for SARS-CoV-2 entry.
- To assess the therapeutic potential of AT, alone or activated, in combating SARS-CoV-2 and related coronaviruses.
Main Methods:
- Molecular docking simulations to predict AT binding to TMPRSS2.
- Enzyme activity assays to confirm TMPRSS2 inhibition by AT.
- In vitro assays using various coronaviruses (SARS-CoV, MERS-CoV, hCoV-229E, SARS-CoV-2, Omicron variants) to assess AT's inhibitory effects on viral entry.
- Lung cell infection models with SARS-CoV-2.
- Experiments involving activation of AT with anticoagulants (heparin, fondaparinux).
Main Results:
- Antithrombin (AT) was identified as a broad-spectrum inhibitor of coronavirus infection.
- Molecular docking and enzyme assays confirmed that AT binds and inhibits TMPRSS2, a critical protease for priming the viral Spike protein.
- AT effectively blocked entry mediated by the Spike proteins of multiple coronaviruses, including SARS-CoV-2 and its variants like Omicron, and suppressed SARS-CoV-2 lung cell infection.
- Activation of AT with heparin or fondaparinux significantly enhanced its anti-TMPRSS2 and anti-SARS-CoV-2 activity.
Conclusions:
- Antithrombin is an endogenous inhibitor of SARS-CoV-2 and may play a role in COVID-19 pathogenesis.
- AT's ability to inhibit TMPRSS2 offers a novel mechanism for broad-spectrum antiviral activity against coronaviruses.
- The findings suggest that native and activated antithrombin could be repurposed as a potential therapeutic strategy for COVID-19 treatment.
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